I mean it's not like the comic panel is in motion, and the cylinders are all drawn the same. The cylinder disappears when she gets to the access corridor and sees the Alien, then when she gets back she's got her hand on the forward bottle.
Easy enough to read it as flamer fuel and not coolant but whatever, this is all a tangent. The way the comic plays out gives An easy way to fix the continuity issue
My favourite continuity issue in the comic is the Alien's size. Man sized? f**king giant? Whatever makes the panel pop.